Methods and apparatus for metal rolling

ABSTRACT

A WIRE OR ROD REDUCTION MILL HAVING THREE-ROLL STANDS WHEREIN FIRST THE WORKPIECE IS REDUCED TO AN EQUILATERAL TRIANGULAR SHAPE, THEN A NON-EQUILATERAL HEXAGONAL SHAPE AND FINALLY ROLLED ON ROLLS HAVING CURVED NON-CIRCULAR GROOVES.

NOV. 9,1971 BlNDERNAGEL ETAL 3,618,354

METHODS AND APPARATUS FOR METAL ROLLING Filed May 6, 1970 mvzmons Ali Bindernogel & Werner Demny United States Patent U.S. Cl. 72-224 4 Claims ABSTRACT OF THE DISCLOSURE A wire or rod reduction mill having three-roll stands wherein first the workpiece is reduced to an equilateral triangular shape, then a non-equilateral hexagonal shape and finally rolled on rolls having curved non-circular grooves.

This invention relates to methods and apparatus for metal rolling and particularly to methods and apparatus for rolling wire, rod and the like products.

The rolling of metal wire and rod is a very old practice and has been practiced with a great variety of rolling techniques. For example it is known to use 3-roll passes in light section rolling mills and wire rod mills with all passes being 3-rol1 passes coupled with a triangular to round rolling sequence. Similarly it is known to use a bar stretch rolling mill using a mill with a 3-roll passes and a sequence of round, triangular and round. These mills and pass sequences will produce the desired product but they are of greatly limited utility and are usable only for the particular sequence for which they were designed. Moreover, they are subject to undesirably high wear at the sizing pass rolls, which in turn requires large expenditures for maintenance, replacement parts, etc.

The present invention provides a stable, twist-free rolling of the stock through the mill with any desired pass sequence and with a markedly increased roll life, particularly at the finishing passes.

Preferably we provide a succession of two 3-roll fiat pass mills and at least two 3-roll mills having the rolls provided with a groove having a variable radius from side to side, e.g. an elliptical, parabolic, hyperbolic or the like curvature, said flat pass mills being arranged so that the first such mill rolls a generally equilateral triangle of the stock and the second flat pass mill rolls the apices of the triangle at about half the reduction of the first flat roll pass mill to provide a non-equilateral hexagonal section on the stock and one of the 3-roll mills having a radiused groove has its largest radius at the bottom of the roll groove and the other has its smallest radiused groove at the bottom of the roll groove. Preferably the mill with the groove having the largest radius located at the bottom is next adjacent the second flat roll pass mill and the last mill has a radiused groove with the smallest radius at the bottom of the groove.

A characteristic of this invention is that between the last 3-roll flat pass of the conventional rolling mill and the sizing stands an additional 3-roll flat pass has been arranged, which takes only half the reduction as the last preceding 3-roll flat pass. The longer sides of the resulting unequilateral hexagon section of the rolling stock are advantageously located in the roll gaps. Such a 3-roll pass, arranged and designed for a smaller reduction will stabilize the rolling stock and guarantee twist-free rolling. The rolling stock thus will pass through the guides without touching the same, except for the front ends. Resulting from a smaller sectional reduction is a much lower wear of the rolls and thus a higher roll life. Expenditures for maintenance and replacement are thus considerably lowered.

It is a further characteristic of this invention that the rolls of the last 3-roll sizing pass have a groove which is elliptical. parabolic, hyperbolic or with various radii in such a way that the smallest radius is located at the ground of the roll groove. A pass design with such shaped rolls makes possible that the rolling stock coming from the last pass of a rolling mill can be guided twist-free into a sizing pass and finished therein. According to the prevailing requirements the rolling stock can also be guided twist-free through several such sizing passes.

The invention is further characterized that the rolls of the 3-roll sizing pass arranged between the last 3-roll flat pass and the last sizing pass are formed in such a way that each roll groove is shaped elliptical, parabolic, hyperbolic or with various radii in such a way that the largest radius is located at the bottom of the roll groove.

In the foregoing general statement we have set out certain objects, purposes, advantages and characteristics of my invention. Other objects, purposes, advantages and characteristics of the invention will become apparent from a consideration of the following description and the accompanying drawings, in which:

FIG. 1 is a schematic drawing of the 3-roll flat pass mill having a smaller reduction used in the first step after forming a triangular section;

FIG. 2 is a schematic drawing of a 3-roll sizing pass with a larger radius at the bottom of the roll groove; and

FIG. 3 is a schematic drawing of a 3-roll sizing pass with a smaller radius at the bottom of the roll groove.

Referring to the drawings, a rolling stock 1 comes from the last 3-roll flat pass mill of the conventional rolling mill is guided into a 3-roll flat pass mill made up of rolls 2, 3 and 4 arranged to act on the apices of the triangular bar coming from the said last 3-roll flat pass mill and to take about one-half the reduction of the preceding mill pass. This 3-roll pass (2, 3, and 4) forms the rolling stock 1 into an unequilateral hexagon section and positions it in such a way that each of the three sides (5, 6, and 7) are located opposite to the respective roll gap (8, 9, and 10), while two shorter sides of the rolling stock hexagon are located at the rolls (2, 3, and 4). The rolling stock 1 formed by the rolls 2, 3, and 4 as shown in dotted lines on FIG. 2, moves in stabilized position into the sizing pass consisting of the 3'rolls 11, 12, and 13. Each roll of this sizing pass has a curvature which is elliptical, parabolic, hyperbolic or some other suitable radii, where the largest radius 14 is inscribed at the bottom of the roll groove 15.

The rolling stock 1 shaped by the sizing pass 11, 12, and 13 as shown dotted in FIG. 3, is now guided into the last sizing pass consisting of the 3-rolls 16, 17, and 18. Each roll of this sizing pass has a curvature which is elliptical, parabolic, hyperbolic or consisting of various radii, where the smallest radius 19 is inscribed at the bottom of the roll groove 20.

The invention is not limited in form and arrangement as shown here, but offers within the framework of this invention among other things the possibility to guide the rolling stock coming from the last pass of a rolling mill directly either in one or several sizing passes. The calibration can be used with or without 3-roll passes. The rolling stock is always twist-free guided. There is furthermore the possibility to use this calibration in conjunction with a rolling mill or similar equipment, or to use this calibration at any other place in a suitable manner independent of such a rolling mill.

We claim:

1. The method of sizing wire and rod from metal stock comprising the steps of:

(a) rolling a metal stock to a cross section substantially an equilateral triangle in form,

(b) rolling the apices of said triangular cross section under a reduction substantially half of that used to form the. triangle to produce a cross section in the metal stock in the form of a nonequilateral hexagon,

(c) rolling the nonequilateral hexagon in a mill having grooved rolls, the work faces of which are formed with varying radii from edge to edge the largest radius being at the bottom of the groove, and

(d) rolling the product of step (c) in a mill having grooved rolls, the work faces of which are formed with varying radii from edge to edge, the smallest radii being at the bottom of the groove.

2. The method as claimed in claim 1 wherein all rolling is done in the 3-roll mills.

3. The method as claimed in claim 1 wherein the midpoint of the smallest sides of the nonequilateral hexagon substantially correspond to the junction of the rolls in step (c).

4. A rolling mill for sizing wire and rod comprising a first 3-roll flat pass mill for rolling a substantially equilateral triangle section in stock passing through it, a second 3-roll fiat pass mill receiving the rolled stock from said first mill at an angle such that it rolls the apices of the stock in a reduction substantially one half that of the said first mill to produce a nonequilateral hexagon, a first 3-roll radius pass mill receiving stock from said second fiat pass mill, said first radius pass mill having rolls with a radiused groove in which the radii vary from edge to edge, the largest radius being at the bottom of the groove and a final 3-roll radius pass mill receiving stock from the first 3-roll radius mill, said final pass mill having rolls with a radiused groove in which the radii vary from edge to edge, the smallest radius being at the bottom of the groove.

References Cited UNITED STATES PATENTS 1,987,324 1/1935 Catterall et a1. 72-234 3,380,278 4/ 1968 Dilling 72-224 MILTON S. MEHR, Primary Examiner US. Cl. X.R. 72235 

